Husband-and-wife architects Tod Williams and Billie Tsien were the perfect team for this vest-pocket New York City museum. Their famous feel for craft and material is something that folk artists understand. But their exercises in stone, glass and ingeniously textured metals are carried out within a modernist idiom that never looks quaint or "folkloric." Who knew you could work so many delightful configurations of space and surprising vistas plus three staircases into a relatively small building? It's a jewel-box museum that's a jewel in itself.